As a high-capacity nonvolatile memory device, the NAND flash memory has been widely used. However, with the device miniaturization, the NAND flash memory has been approaching the physical limit. Recently, new memories such as ferroelectric memory, magnetoresistive memory, phase change memory, and resistance change memory have been developed. Among them, the resistance random access memory (ReRAM) is drawing attention.
A memory cell of the resistance random access memory typically includes a rewritable memory layer (rewritable layer) and wiring layers sandwiching the memory layer. For instance, in the case of using the memory cells as a cell array, an electrical bias or current is externally applied to perform writing, erasing, and reading. To this end, word lines and bit lines are provided above and below the memory cell. In the resistance random access memory, with the miniaturization of memory cells, memory cells with higher reliability have been required.